1. Field of the Invention
The invention pertains to a lock which is installed in the area of the door or hatch and has a rotary catch. A locking part is located on the door post, and when the door or hatch is closed by hand, the locking part travels into the rotary catch, thus pivoting it initially from a spring-loaded open position into a pre-latching position. The pre-latching position of the rotary catch is secured by a spring-loaded pawl. Then the motor of a door-closing assist mechanism is turned on by control means. This mechanism, operating by way of a gearbox and a cam, moves the rotary catch from the prelatching position to the main latching position. The main latching position of the rotary catch is also secured by the pawl, which engages with a main notch provided on the rotary catch.
2. Description of the Related Art
Locks with motorized closing and opening mechanisms are known (WO 98/27301 A2), in which the gearbox has two takeoff routes, between which a gear element is installed with freedom to pivot. This lock has proven to be reliable, but it is bulky and expensive.
A lock of the type indicated in the introductory clause of claim 1 is known (DE 101 33 092 A1), which is less expensive that the previously described state of the art. In this known lock, the gearbox of the motor is engaged at all times and acts on two cams, one of which acts as a closing aid. This cam has a lobe, which, upon rotation of the motor, travels in one direction behind a shoulder of the rotary catch and, as previously mentioned, turns this from the-pre-latching position into the main latching position under the action of the motor. As a result, the locking part engaged in the rotary catch is also carried along, and the door is brought into its final closed position on the vehicle.
In the case of a lock of a different type (DE 43 11 786 C2), in which the rotary catch has neither a preliminary notch nor a main notch, the spring-loaded pawl is mounted on the free end of an actuating rod, the other end of which is driven by a motorized crank drive. A permanently supported rocker acts on the free end of the actuating rod. As the door is being closed and the rotary catch is being carried along, the movable pawl, which is spring-loaded, drops behind a shoulder of the rotary catch. When the motorized crank drive starts to turn, the pawl, which moves along with the actuating rod, carries the rotary catch along until it reaches the fully closed position. Then the motor stops, and the pawl remains engaged with the shoulder. At the same time, a lobe on the pawl travels under a fixed stop, which stops the movement of the free end of the actuating rod. The fixed stop is necessary so that, when the rotary catch is in the closed position, a hand or the motor can lift the pawl out of the rotary catch and hold it until the spring-loading force acting on the rotary catch can move the catch into its open position.
The invention has recognized that the disadvantage of the known lock is to be found in the direct connection between the cam and the rotary catch. For this reason, it is necessary to develop a new lock for each different type of vehicle to accommodate different sets of relationships. This not only requires the production and assembly of different lock elements, but also demands more complicated inventory control and increases the difficulty of repairing defective locks. Thus, for example, in the case of the previously mentioned known lock, it is not possible, when a change is made in the reduction ratio between the motor and the gearbox, simply to replace the gear wheels, without at the same time providing the rotary catch with a different external profile, in which the shoulder for the eccentrically moving lobe occupies a different position. In the case of the known lock, it was therefore necessary to develop a separate lock for each vehicle to accommodate the specific circumstances and, if necessary, to keep such locks in inventory. This led to a large amount of manufacturing work and to complicated inventory management.